You didn't misunderstand: The new version of the cheat sheet was meant to do exactly that: For example, physical pin 11 on the ATTiny2313/4313 is PD6 (when programming in low-level avr-gcc) and is assigned to Arduino pin number 8: This is written as PD6/D8 in the cheat sheet.

You won't be able to use the inverted PWM for Arduino, but the sheet covers both Arduino pin numbers and normal port numbers (that's why it says D3/PB3). That said, there should be a note saying that PB3 is a "special" PWM pin.